We didn't intend to hide it but a lot of our customers act surprised when we show it to them. Universal reaction is "whoa, I didn't know I can do that!". Here is a quick description:

At a decision point you often want to see not only the current range of a player having a decision to make but also specific sub-ranges for every possible decision. For example in response to a continuation bet you may want to see a raising range, a calling range and a folding range. To do that it's not necessary to navigate to those decisions. It as easy as one click.

Here is an example: it's a 3-bet pot. The board is As 4d 4c, OOP player just made a continuation bet and we want to see what raising/calling/folding ranges are in response to that:

That's it. You can then right-click the 13x13 grid to copy chosen range and paste it into our range selector to take a closer look (available in Tools->Select Range)